Souls Shining Like Stars
by Bookworm Gal
Summary: Prequel to the game and "Souls Shining In The Dark." Long before Frisk, Asriel, or Chara, there was a skeleton named Gaster who wanted to help monsterkind. He invented the Core, found the love of his life, and started a family. Everything seemed perfect. Then everything started to fall apart. And it continued to get worse for his entire family for a long time.
1. Exploring

**So… Yeah… I worked out all this backstory and timeline stuff while working on my story "Souls Shining In The Dark" that I ended up getting inspired to actually write out a prequel. You know, something showing the past for the skeleton family that we all like so much. And it gives me more excuses to do some worldbuilding and explore some ideas. Not to mention develop some characters who were only referenced or barely showed up in my other story. That's always fun.**

 **The story is set before the events of the game. To give you a brief idea of the time frame involved, this story will start with Gaster when he's a teenager (around 13) and go all the way up to when Frisk is in the Underground. That's a lot of time to cover. But I think it'll be worth it.**

 **Quick warning though. Due to the fact that this is a prequel, there are some horrible fates that can't be avoided. Asriel and Chara have to die. Sans and Papyrus will lose their mother. Gaster will fall into his creation and disappear from reality, along with his followers. If you're not prepared to deal with having your emotions occasionally twisted into a pretzel, then this may not be the story for you. Whether the good outweighs the tragic parts is up to you.**

 **All right, in case it wasn't obvious, I'm not Toby Fox. I had nothing to do with the creation of "Undertale" or the characters in that game. The characters invented specifically for this story, however, are mine. But you're certainly welcome to borrow them should you want.**

Souls Shining Like Stars

"You know our parents are going to kill us when we get back, right?" said Erik, not for the first time.

The young crab-like monster kept his claws clutched together, the stalks of his eyes twisting as he looked around. He'd been relatively difficult to talk into the journey. But even with his hesitation and his certainty of how much trouble they would be in, he agreed to come when he found out who else would be going.

"You keep saying that. If you were _really_ worried, you would have turned back a couple days ago," Trixie said, the bunny-shaped monster circling her shorter companion as her excessive energy kept her nearly constantly moving. "But we all know there are always risks if you want an adventure."

While Erik only wore a yellow scarf wrapped awkwardly around his stout body, she was wrapped in a sturdy brown coat that she claimed went nicely with her lighter colored fur. The three young monsters, the teenagers recently out of stripes, knew that the caverns right outside of Home were supposed to be cold and had dressed appropriately when they snuck out. He'd chosen a thick gray sweater that even managed to cover his neck, though the temperature was less of a problem for him than it was for his companions. Just like with their backpacks filled with food and the scrolls of parchment that he used to map their journey and record their discoveries, he wanted everyone to be prepared for anything.

But they had long since left the cold and snowy caverns with the tall trees that grew with only the limited light of the Underground, light that was reflected off the snow and seemed to make it seem a little brighter. Now the trio were exploring a series of darker and wetter chambers. They kept finding various waterfalls and they had to sometimes wade through the shallower sections of water. Sometimes the ceiling dripped down in constant drops of water, but in other places the ceiling and walls were covered in shining rocks that glittered brightly. And then there were the blue flowers that mimicked their voices, which all three of them tested for quite a while before they finally moved on.

And then there was the huge waterfall dumping human objects in piles. All three monsters were temporarily awestruck as they investigated the items. Humanity had certainly progressed in the centuries since monsters were trapped. While some objects were similar to inventions and developments that monsterkind had worked on in the time since, others were completely foreign. The trio stuffed their backpacks full of the most useful or most interesting items. He especially liked the thick packets of bound parchment with writing and illustrations on them. It certainly seemed more practical than scrolls for storing a lot of information together. He made certain to fit as many as he could until he could barely carry his backpack.

Trixie was right when she called it an adventure. This was the most amazing thing any monster had seen in at least a few hundred years.

No one had explored these tunnels in generations. Not because it was against any laws, but because of fear. They all knew the story. They knew about the war and how many families were torn apart by death. And once sealed behind the Barrier, all the monsters traveled to the point farthest from the entrance to the Underground. Only once they were far away in case humanity decided to finish what they started did the monsters create Home.

It was a decent place to live, albeit unimaginatively named by their king, but it seemed pretty small now. The generations since the war led to some crowding issues. Everyone lived in close quarters with each other. Rooftop gardens and similar steps were essential because there was nowhere else to produce those necessities. Everyone knew every single brick and stone in the place and had memorized the solution for every puzzle in the area. And after spending their entire lives in the increasingly ancient city, exploring the rest of the Underground appealed to the teenagers.

After all, if humans ever intended to storm through the Barrier and kill off the remaining monsters, they would have done so by now.

Well, teenage rebellion explained why Trixie decided to join him on his multi-day hike through unknown territory. And Erik came along because Trixie did.

But his reasons for conceiving the crazy idea in the first place were in some ways far simpler. Why he invited his friends to journey through the rest of the Underground, mapping the various caverns and chambers they found and recording the more unique features? Because he'd wanted to know more. All the questions he'd asked that no teachers could answer and no one else tried to uncover would never be solved if no one ever looked further. Exploring more of the Underground might only be a start, but it was _something_.

"Hey, is it just me or is it getting warmer?" asked Erik.

"He's right. I'm getting toasty," Trixie said, finally shedding her coat and revealing a tan shirt underneath. "If it gets much worse, I'm heading back to that snowy place instead."

"You only like it because you have fur."

"And you… you have big pinch-y claws. What's your point?"

"My— _Whoa_! Look at that!"

Erik's shock was well warranted. They'd just entered a huge chamber, one that opened up higher than before and stretched out. The cavern was bright, negating the need for glowing crystals or fire magic to light their path. The heat and orange light came from somewhere below.

Curiosity coaxed them to creep to the edge of the cliff and look. He couldn't keep his jaw from dropping at what he saw. Below was magma, the molten substance stretching out like all the stories about oceans. The huge chamber seemed to be covered in magma.

While Erik and Trixie seemed a little intimidated by it, the skeleton monster stared at the magma in complete fascination. He knew that deep within the earth, stone grew hot enough to melt. Even hidden away in Home for so long, monsters still remembered and taught that piece of knowledge. But he saw so much more than a simple factoid shared by a teacher. He stared at the source of so much heat, light, and power. The sheer potential made his bones nearly shake with excitement.

His teachers said energy can change, that it can be converted from one type to another. They mostly used the example of how magical energy could produce heat and light in the form of fire magic. But there had to be other examples.

And with all this magma and all that potential power, there must be a way to use it. There must be a way to harness that energy and use it to help everyone. Things that monsters had to perform with magic… Could they use the energy from all this magma to do it instead? Why had no one tried it before? Long ago, when monsters journeyed through the Underground for the first time, they would have seen the magma and yet no one ever tried to make use of an infinite power source. It seemed like such a waste.

" _Hey_ ," shouted Trixie, her tone making it clear she'd been yelling for a while. When he looked up, she continued, "As I was saying, we can't go any farther this way. Wherever everyone else got across, it wasn't here."

She was right. They were at the edge of a cliff. Further out were little islands of solid land in the ocean of magma. But if there had ever been any natural bridges across or around the magma, they had long since crumbled away. They couldn't go anywhere except back.

"Guess that's the end of our adventure," Erik said. "Mom is going to kill me when we get back though."

"Worth it," said Trixie. "It was completely worth it."

He didn't immediately respond, too busy trying to sketch out as much of this final chamber as he could while he continued to grin about the magma. His mind kept devising various ideas, all sparked from the immense potential of the molten substance. He was not going to forget this place anytime soon.

Finally, as he put the last touches on the map and rolled up the parchment again, Gaster said, " _I agree. It was worth the trip._ "

* * *

" _WINGDINGS GASTER, YOU ARE IN SO MUCH TROUBLE! DO YOU HAVE ANY IDEA WHAT YOU PUT ME AND YOUR MOTHER THROUGH?_ "

He cringed both at the use of his full name and at his father's loud and strongly-accented voice, two things he really didn't want to hear while attempting to sneak back into the house. Marlett and most of that side of the family could barely be understood by the average monster at the best of times. His son's accent only grew troublesome when he was excited or upset. When _Marlett_ was upset, even his wife and Gaster struggled to understand his words.

" _I left a note_ ," he mumbled.

" _A NOTE? DO YOU THINK THAT MAKES UP FOR THE FACT YOU DISAPPEARED FOR NEARLY A WEEK? YOU COULD HAVE DIED AND NO WOULD HAVE EVER FOUND YOUR DUST. WE WOULD NEVER EVEN KNOW WHAT HAPPENED TO YOU. IS THAT WHAT YOU WANT?_ "

The tall and broad skeleton stood next to the table, arms crossed and glaring at his son. He didn't share Gaster and Mistral's eye-lights, so his narrow eye sockets were always dark. And glaring always seemed more intimidating without eye-lights. So when the older skeleton in rough white sweater scolded his son, it did manage to spark a little guilt about what he put his family through.

That didn't stop him from trying to defend his actions at least a little.

" _I went with Erik and Trixie. We were perfectly safe and nothing bad happened._ "

Stepping forward from her place next to husband and smoothing out her blue dress, Mistral said, " _ **And what if something happened to your friends because of your idea? No one can predict an accident and not everyone is as strong as you are, my precious boy. Perhaps you would be able to shrug off a fall from a great height or a cave-in, but they could have been seriously hurt.**_ "

" _AND NO MATTER WHAT YOU MAY THINK, YOU'RE NOT INVULNERABLE_ ," continued Marlett. " _BOSS MONSTER OR NOT, YOU COULD HAVE STILL DIED OUT THERE! FOR SOMEONE SO SMART, THAT ENTIRE DECISION WAS INCREDIBLY STUPID._ "

" _All right, I get it. Running off like that was wrong_ ," Gaster muttered. " _Sorry, Mom and Dad. I still think you worried too much though._ "

His mother stepped even closer and wrapped her arms around him in a hug. While Mistral had thinner bones and a narrower body shape overall than her husband, she shared Marlett's height. So far, Gaster seemed to be taking after her in appearance. But until he hit his final growth spurt, she was still a little taller than her son. The difference in height made it easy for her to gently press her forehead to the top of his skull: the equivalent of a kiss for monsters without lips or the ability to properly nose nuzzle.

" _ **My precious one, you'll understand someday. When you're a parent, you always worry about your children.**_ " She pulled back a little so she could look him in the eye socket. " _ **We were so afraid that something would happen to you out there and no one would be there to help. We didn't know if we would ever see you again.**_ "

" _WE KNOW YOU'RE GROWING UP AND CAN TAKE CARE OF YOURSELF TO AN EXTENT_ ," said his father, calming down from his original outburst. " _BUT WHEN WE WOKE UP THAT MORNING AND YOU WERE GONE…_ "

" _ **Please don't ever scare us like that again**_ ," Mistral said, reaching up to cup his face. " _ **Don't make us go through something like that ever again.**_ "

Seeing the almost haunted look in his parents' eye sockets, Gaster knew he'd messed up. He should have handled this differently. While he knew they would be mad about him disappearing, he never really considered what thoughts would run through their minds. He didn't realize how their imaginations would conjure horrible possibilities. He never thought what his quest for knowledge would do to his family.

He dropped his head and said quietly, " _I'm sorry. I really am._ "

" _WE KNOW YOU ARE._ "

" _ **We're just so happy you're back safely.**_ "

" _BUT YOU'RE STILL IN BIG TROUBLE._ "

Shifting his backpack a little, Gaster said, " _Yes, I know._ "

* * *

Their home wasn't particularly large. No one had that much room anymore. Over the centuries, the houses were split into smaller and smaller domiciles. Multiple families would share the same building that was once considered a home for a single family. Gaster's family lived on the upper floor with three rooms while a family of Moldsmals lived below them and another family consisting of a stone elemental, a reptile monster, and their shiny diamond-like daughter occupied the ground floor. On the rooftop, they all maintained the garden where they grew hardy vegetables, strains of cotton magically encouraged and cultivated to thrive in low light, and other necessary crops for the household.

There was no room in Home for wide-scale crop growth or production. Everything was done on a personal level because there was no space for anything more. No one was starving, but it wasn't ideal either.

Since space was a valuable resource, it wasn't surprising that Gaster's room was small. There was barely room for his bed. His clothes and belongings were stored on the shelves he'd attached to every wall. Mostly he kept his scrolls there, but he had a feeling his new prizes from the trip would soon join them.

Well, at least until he copied everything. Then he'd donate the bound manuscripts to the school or something. He wasn't greedy, after all.

Sitting on the edge of his bed, Gaster started emptying his backpack. First, he pulled out his maps. Every tunnel and cavern they explored was carefully recorded. Eventually he would have to go back and transcribe his notes into proper letters that other monsters could read.

He hated doing that. Trying to read regular script would always give him a headache after a while. Normal letters just always seemed like a strain to read, an issue his father occasionally admitted to possessing as well. Gaster had eventually designed an entirely new alphabet that was easier for him to deal with and used it for all his personal notes, though he was still forced to use normal letters when sharing with others. So if anyone else wanted to read the map, Gaster would need to fix it. It would be time-consuming, but necessary.

Next, he pulled out his general notes about the journey. The various plants, the unique features for each section, and so on were meticulously recorded. Again, he would have to transcribe everything. But he looked forward to sharing it.

Finally, Gaster removed a stack of thickly bound parchment. Or at least, something similar to parchment. Each one was thinner and more delicate than normal parchment. Perhaps humans used a different material? He could see some damage from the water, the ink smudged in places and the not-parchment sticking together occasionally. But the outer cover would protect the inner contents slightly, which he considered to be a practical solution. The entire design was practical. Hopefully monsterkind would eventually adopt it in the future.

He tried to grab every piece of educational text he could find in those piles of human creations. Descriptions of science, history, and even a dictionary were all carefully collected. Even seeing what new words that humans had invented could provide a clue about the various developments in the past few centuries. There was no reason to think that two species would make the same discoveries and inventions after being separated for so long.

Gaster considered starting with the dictionary, but just thinking about reading all that small print in the standard alphabet was making his skull hurt. He would just use it for the moment to clarify things as he read something more interesting than a list of words. He pulled out one that seemed to be designed to teach science to children or teenagers. There was even a glossary at the back for certain terms. That should make a good foundation for whatever he might be able to discover with these texts.

* * *

Toriel loved her husband and he was wonderful at dealing with people, especially when it involved convincing them to go along with an idea or encouraging them towards a course of action. But he wasn't always the best at the logistics, management, and administrative aspects of ruling. If she was feeling a little grumpy with him on that particular day, she might even say that he was just barely better at it than he was at naming things. But she was fairly adept at handling such matters after so long. Both their marriage and their leadership over the monster was an equal partnership.

Not to say being co-rulers over all of monsterkind didn't have its challenges for them. They were thrust into the roles unexpectedly soon during the war, Asgore's parents dying in battle shortly before humans claimed victory. Married for only a few months, the new king and queen began their reign by leading the remaining monsters deeper into the Underground while the seven human wizards entombed them behind the Barrier. It was… a challenging way to begin, but the two of them worked together to organize the monsters and help keep their hopes up. It wasn't perfect, but everyone was managing.

At least it worked for a while. Toriel knew that something would have to be done soon. While Home was enough at the beginning, letting them feel safe and comfortable in their new settings, the monsters were outgrowing the city. More and more, the issues of overcrowding could not be ignored. Toriel and Asgore had tried to discuss possible solutions and it was becoming clear they would have to eventually leave.

They would have to create new settlements in the rest of the Underground. And to do that, they would need to scout out possible locations that were both safe and spacious. They would need teams to explore, to build, and to accept the challenges of facing life outside the familiar city. Toriel could already imagine the logistics nightmare.

But even with that problem looming on the horizon (if there _was_ a horizon in the Underground), daily life continued. And for the king and queen, that meant open court for any citizen who wished to present their grievances. Asgore and Toriel hated the idea of anyone being unhappy when there was something that could be done and it was helpful to stay on top of problems before they could grow and fester. Some days would have a lot of monsters while others may have none.

Today, only a single monster came to the balcony that overlooked Home and had served as a throne room ever since they surrendered the old building for more housing. With Toriel and Asgore in their identical thrones, he approached with a large box in his arms. He was a young skeleton in a gray turtleneck sweater. He was tall and extremely skinny, even for his kind. And he looked extremely nervous about speaking to royalty, his eye-lights shrinking slightly as he stepped forward. First comers often were a little anxious.

"Howdy," greeted Asgore, smiling at him reassuringly. "What can we do for you?"

" _Actually, I think I might be able to help you, Your Majesties_ ," he said, a strange accent tinting his voice. " _It's a bit of a long explanation, but I've been working on a way to help the Underground._ "

"Oh? How so?" asked Asgore, encouraging the monster with his tone.

Digging into his box, the skeleton pulled out a glass orb attached to a smaller box. Inside the orb, she caught a glimpse of a thin coil of metal that was not much thicker than a strand of her fur. Toriel leaned forward as her curiosity grew.

" _Based on the books retrieved a few years ago, humans have been harnessing the power behind the lighting storms on the Surface. 'Electricity.' I've managed to reverse engineer it_ ," he said, flipping a small handle on the side of the box.

Neither of them were prepared for the bright light to appear, shining from the glass orb with a strange intensity. Both of the goat-like monsters flinched and squinted their eyes against the sudden glare. It was brighter than candles or the magic crystals normally used for light. The only thing Toriel could compare it to was her distant memories of the sun.

Setting the box down, the young skeleton continued hurriedly, " _That's just a small stored amount of electricity from my experiments. We could produce more. A lot more. And all monsters would have access to it and could have light like this for their homes. And that power could be used for other purposes. It's just energy in a form that can be stored or moved easily. How we use it is only limited by our creativity and inventiveness. This is just a starting point._ " His hands were gesturing excitedly as he spoke and his accent had grown stronger, forcing Toriel to focus more closely on the words. " _I've been working on a design for the past few years to do this on a larger scale. To give monsters limitless power to use however we want._ "

He pulled out a schematic from his container and held it up to demonstrate. Toriel couldn't completely understand the blueprints and what they were showing, but she could recognize a lot of careful planning and work when she saw it.

" _It would take some work and it might need some adjusting from what my plans show, but it should be easy to expand it in order to keep up with our increasing energy requirements over time_ ," he explained, every phrase punctuated by a hand gesture at a different point on the schematic. " _It would require leaving Home though. The design is meant to be built near the magma so that it can convert the thermal energy into magical energy and then into electrical energy. Though we can also use the magical energy produced itself if we need it. But in order to construct it, we'd need easier access to the molten core of the mountain. We would need to develop infrastructure to travel between Home and the magma chamber. We would need easier paths to transport material for building and monsters to construct it._ "

Still speaking too quickly to be easily interrupted, the skeleton dropped the schematic back into his box. Then he pulled out a large piece of parchment and started unfolding it.

" _Now, I know this seems like a lot of work for some lights, but it'll transform everyone's lives. And other than building the device itself, the biggest requirement would be the infrastructure. Like laying cables to transport the electricity and sturdy paths for travel. At a minimum, we would need to construct bridges at these key locations._ "

Then he started gesturing at a _map_. Toriel's hand flew to her mouth while her husband's jaw dropped in shock. The young skeleton was holding a map of the Underground. A very detailed and through map of the Underground, one that covered the tunnels far beyond those surrounding Home. Basically, the information they needed to start hunting for potential sites for future settlements was right there in his bony grip.

"Where," asked Toriel, cutting off his enthusiastic description and abruptly reminding the skeleton who his audience was, "did you get that?"

Ducking his head, he stammered, " _I drew it, sir. Ma'am. Your Majesty. You see, my friends and I explored the rest of the Underground a few years ago. Remember all those books and stuff? The human ones? We brought them back, Your Majesties._ "

She remembered. Toriel remembered the entire thing because it really shook up the routine. Three distraught families, after exhausting all other options days ago, approached their king and queen in the hopes they'd be able to help. Three young teenagers had vanished and could not be found in Home anywhere. They even searched in the deepest part of the Underground, where a thin stream of light from above shone through the opening in the stone. While the Barrier still blocked it as an exit, some young monsters did like seeing it. But the missing teenagers weren't there. Just as Asgore and Toriel prepared to send the Royal Guards out to search in the closest caverns, news came that they'd returned on their own.

The "mysterious" donation of human books and artifacts to the school not long after didn't take much detective work. But they were appreciated. Monsters were quick to investigate and attempt learning from what they discovered. Bound books were quickly replacing scrolls, though they still used parchment since they didn't have the wood pulp or experience to make paper yet. And while monsters had long since exceeded what humans apparently knew concerning magic and Souls, there were some branches of science and technology that monsters had never imagined. Their scientists were still trying to learn and extrapolate what they could from what those teenagers found.

And this young skeleton had already figured out enough to start building off the information and incorporating it with magic, designing something to completely transform their lives in the Underground.

Assuming he was right. And Toriel had a feeling he knew what he was talking about.

"And your map?" asked Toriel.

" _While I was out there, I mapped the tunnels as we explored. I sketched them out and took notes. I was curious, Your Majesties._ "

"Golly, that's impressive. How old were you at the time?" Asgore asked.

" _Thirteen, almost fourteen_ ," he said. " _I'm sixteen now, if it matters, Your Majesties_."

Staring at the young skeleton, Toriel said, "I would like to take a close look at your map for a moment. Please let me see it, will you not? I will return it undamaged."

He hesitated briefly, but he recognized a royal command when he heard it. The young skeleton held out the large piece of parchment and Toriel accepted it delicately. She could see where it had been folded and refolded repeatedly over time. Every chamber, tunnel, intriguing landmark, and important feature was carefully recorded. Strange markings appeared at different points, but normal writing appeared below to provide a translation for his notes. The use of a cipher was intriguing, but the detail of the map was far more important.

This was exactly the level of detail they needed to plan for proper expansion. And he'd done it as a thirteen-year-old.

"What is your name, young one?" asked Toriel slowly,

" _Gaster, Your Majesties_ ," he said, bowing slightly. " _W. D. Gaster_."

Smiling at the young skeleton, Asgore asked, "Well, Gaster, do you think we could have a copy of your map to keep?"

" _Yes, Your Majesties_ ," he said, something shifting in his posture to reveal his disappointment. " _I have copies at home._ "

"And we would appreciate copies of your design for your invention, of course," said Toriel. "It would be a shame to risk damaging the original."

That managed to perk him up, his smile brightening at the reassurance that they were interested in his design. His skull bobbed up and down in hurried nods. For a moment, he looked like an excited child rather than just an excitable teenage scientist. It was hard not to chuckle.

" _Of course, Your Majesties. I would be happy to provide any materials you might require_ ," Gaster said, his hands starting to twitch with nervous energy.

Unable to contain her curiosity much longer, Toriel decided to learn a little more about the young skeleton. While he watched Asgore smile at the map, she took a moment to subtly Check the teenage monster.

 *** W. D. Gaster**

 *** AT: 66**

 *** DF: 66**

 *** Far smarter than his age would suggest, but sometimes gets caught up in his ideas.**

Toriel forced herself not to react. While he was certainly at the age where he would have grown into the Stats he would normally have as an adult, disregarding minor fluxuations through training and resolve, they were still higher than she expected. There was only a limited number of explanation, but one was far more likely than others. She couldn't prove it without seeing his Soul, but Toriel suspected the young skeleton was a Boss Monster.

They were never the most common, even before the war cut down so many monsters. The trait of being a Boss Monster might appear in a single member of a family line before vanishing for generations until it eventually happened again in a new member. The only way to guarantee that a child would be born a Boss Monster would be for both parents to also be Boss Monsters. There might only be a dozen of them currently alive, scattered throughout the population and in a variety of shapes.

While their marriage was by no means an arranged one, Asgore was encouraged by his family to find another Boss Monster as a spouse. It was preferred to have rulers who could look after monsterkind for a long time and wouldn't die of old age before an heir was ready to take the throne. That stability was reassuring to monsterkind. There was also less risk of outliving your spouse. And she and Asgore did love each other, so neither of them saw a problem with how it turned out.

But if Gaster was also a Boss Monster, then he would stop physically aging soon. And unless he had children in the near future, he and his brilliant mind could be around for a very long time. His sheer intelligence and potential were impossible to hide. He could do a lot of good for monsterkind.

Apparently recognizing the same potential in the young skeleton as she did, Asgore said, "You truly know how to make an interesting first impression, Gaster. I believe that we should discuss your ideas more. Perhaps over tea? You clearly have a bright future ahead of you. Have you completed your schooling yet?"

" _I surpassed their lessons a while ago, Your Majesties. I simply didn't inform the teacher of that fact and used the time to further my own studies_ ," he admitted. " _Though the schematic was at the core of my work for the past few years._ "

"Hmm… I don't suppose you've decided on a name for your design yet, have you?" asked Asgore.

"Gorey, _no_ ," she said, knowing it was already too late.

"Come on, Tori. What he said about it being 'the core' of his work gave me a great idea."

 **And so there's the start of this prequel. A little worldbuilding and the beginning of what will someday become the Core. That's a pretty good way to begin the story, right?**

 **All right, just in case you're wondering, here's the inspiration for a few of the names of the characters. "Erik" gets his name simply because I was watching "Phantom of the Opera" at the time I was writing. He got that name for no other reason. "Trixie" gets her name due to being a rabbit-like monster and it has similarities to the name of a breakfast cereal with a rabbit for a mascot.**

 **As for the skeleton names, they are based on fonts yet again. "Marlett" is another symbol font similar to Wingdings. It is mostly used to create user interface icons that are used in the menus and windows and has been around since 1995. "Mistral" is a casual type of font designed to mimic brush and ink, giving the letters a cursive look while seeming very relaxed in style. It is also a rather distinctive font and certainly not something that would be chosen for regular situations like a book report.**

 **Regarding the symbol based fonts like Wingdings and Marlett, since those fonts don't use traditional letters, I've interpreted it as those types of skeletons having a bit of an odd accent.**

 **Anyway, I hope that you like how this story is starting out so far. I have big plans and I'm going to push myself out of my comfort zone eventually. That's right! I'll have to eventually writing something that I rarely explore! A romantic relationship! Gaster has to meet up with his future wife eventually.**


	2. Promoting

**I hope that you guys enjoyed the first chapter. And I certainly hope that you will like how things go from here. There's a lot of time to cover.**

From the moment he brought his ideas forward to the king and queen, everything began changing. Gaster didn't realize what he'd started until it was already in motion.

First, his parents freaked out over the news. They knew he was smart, but finding out their son had an audience with royalty about his work and had been invited back to discuss it further went far beyond what they'd ever expected. Both Marlett and Mistral took a moment to believe his explanation, but quickly became extremely proud. They quickly informed everyone they knew that their son was advising the king and queen. Gaster ducked his head in embarrassment every time, feeling it was an extreme exaggeration of what he was doing. But they were certainly supportive.

They were so supportive that they decided to read some of the human books that he enjoyed so much and inspired his work. While Gaster was happy to see their interest, he did everything in his power short of destroying it to keep his parents away from the one book entitled "Anatomy." He still remembered the shock and embarrassment when he turned the page to the chapter about humans' skeletal structures and encountered a very graphic picture of a skeleton without a hint of clothing. While not every page of the chapter was as vivid, it still revealed more than civilized people showed in public. Gaster feared even years later the very idea of his mother finding out and asking him about the book. That was a conversation he never wanted to have.

Obviously construction on the nearly-named "Core" couldn't begin immediately. But within a few days, a team of monsters were gathered together and given the task of building the first of the planned bridges. King Asgore and Queen Toriel announced to everyone their intentions to expand beyond Home and create new communities for everyone. And while there was some hesitation, most embraced the vision of the future. It gave them hope.

And while that construction project began, Gaster and a few others worked on incorporating the new knowledge from the Surface into their curriculum. It also allowed him to get an objective look at where he was in his self-taught education. To his surprise and that of the others, he managed to reach the same proficiency on most topics as the experts in the fields. There were only a few subjects he still needed to study. And with a little testing to ensure he was completely qualified, he and a few others were given the newly-established title of "doctor."

Expert healers, masters of magical theory, and those with a detailed understanding of both the monsters' established knowledge of science and the new discoveries from humans… Essentially, they gave a title and a white lab coat to those who already deserved recognition. Humans were clever to create the word.

Weeks turned into months and months morphed into a few years. Bridges, the wood harvested from the snowy forests, were raised over several chasms and valleys until monsters could easily and quickly cross the frozen landscape. Eventually monsters would be able to reach the damp and darker caverns without issues. A few of the furry folks started building a few homes near the river. Progress was gradually being made all around.

As had quickly become tradition, Gaster approached the royal grounds for the weekly meeting with King Asgore for tea. He wasn't completely certain how it became so established. Somehow the king just kept inviting him over until it became tradition. Sometimes Queen Toriel would join them and politely inquire about how his remaining education was going, but she couldn't always spare the time from her other responsibilities. So most of the time, it was only him and King Asgore discussing his most recent developments and the progress on the construction while drinking the provided tea.

Which left him mildly surprised to see both members of the royal family waiting for him.

" _Your Majesties?_ " he asked, something in their expressions making Gaster realize this wouldn't be a normal tea.

"Gaster," said Queen Toriel with a nod. "Or I suppose I should call you 'Dr. Gaster" now. That is the correct title we have established now, is it not?"

" _That is correct. We have also nearly worked out a proper set of requirements for other monsters to earn their doctorates_ ," he said. " _Though I have a feeling most will be older than I was. Most monsters don't spend their teenage years trying to adapt human knowledge and technology for the good of monsterkind_."

Nodding at him, King Asgore said, "You are quite right. There is no one quite like you. And even if we haven't begun work on the Core, you've already done a lot of good since you approached us. Not only have you been helping to develop the curriculum for our future generations, but you've also assisted on the designs for the bridges, refining your plans for the Core further, discussing with those who are moving out about the best use of the terrain, and transcribing several of our scrolls into bound books."

" _You've been paying a lot of attention to what I've been doing with my spare time_ ," Gaster said, trying to keep from blushing at the praise. " _I mentioned some of it vaguely during our tea visits, but only off-handedly. We rarely focus on my personal accomplishments rather than more general developments. And I only made copies because I was transcribing versions for my personal use anyway, so making other copies for public use was not much trouble._ "

"My point is that you have done more for monsterkind than most realize and we are quite certain you will continue to make amazing contributions for years to come," said King Asgore. "Tori and I've been discussing it for a while. We believe this is long overdue."

" _I'm sorry? I am afraid I do not understand what you mean, Your Majesties. What is long overdue?_ "

"Just as you now possess the title of 'doctor' to describe your expertise in numerous branches of science," explained Queen Toriel, "we now believe that you should bear the title of the job you are already performing."

He stared at the royal couple. Gaster had absolutely no idea what they were implying.

Well, that wasn't quite true. He had a vague possibility rattling around his skull. The king and queen had advisors of various sorts. Queen Toriel was often meeting with them rather than attending tea.

But Gaster knew he had to be wrong. Regardless of what his parents might think and brag, he wasn't an advisor. Not really. Those advisors were older monsters. Not as old as the royal couple or Gerson who lived a couple streets over, but certainly older than him. True, Gaster was no longer a teenager. And he wouldn't be physically aging again until some distant day when he had children, so he would still look the same when he grew old. But he still couldn't imagine anyone considering him to be old enough to advise them. He didn't have the experience to qualify.

So he must be wrong. Queen Toriel must mean something else. She and King Asgore probably had something completely different in mind. Gaster tried to still his hands' nervous fidgeting. He should calm down. There had to be a different explanation.

" _I… am not certain what you are implying, Your Majesties. What job title are you offering?_ "

"You have advised us on everything to do with science," said Queen Toriel. "While we have several advisors, you would be more specific and you would continue with your other projects."

"How would you like to be our Royal Scientist?" King Asgore asked.

Oh… He didn't expect that. Even when he briefly considered and rejected the possibility of being called an advisor, Gaster didn't think they'd create a new role just for him. As far as he knew, there had never been a Royal Scientist in the Underground and scientific studies were not well-developed before monsterkind was trapped. The title of Royal Scientist did not exist until now, just as the term "doctor" was a new addition to the Underground.

But just as he rather liked how "Dr. Gaster" sounded, the new job title felt right as it rolled around in his skull. He always tried to do something to help monsterkind. All his efforts were to make things better for them. And being the Royal Scientist sounded like it would allow him to always do what he loved. He would be able to continue to study and invent, helping everyone with his work.

He'd never considered something like this for his future. He never thought long-term about his personal future rather than that of all monsterkind. But now that the idea had been presented, Gaster couldn't imagine anything else. It just felt right. It felt right all the way down to the marrow of his bones.

"You do not have to answer immediately," said Queen Toriel gently, mistaking his hesitation for reluctance. "We would not ask you to do anything more than what you already do. We merely wish to give you the correct recognition and standing for all that you do for us. But do not think you will insult us if you should choose not accept the role."

" _No, it is not that, Your Majesties. I mean no disrespect. I am truly honored by this offer. I never considered such a thing. And not simply because I never knew you might desire a Royal Scientist. Or that such a job existed. But it is amazing that you're offering me something like this. It is hard to imagine that I would end up like this when everything started because a teenage skeleton brought you a stack of maps and schematics. Everything has come so far since then and—_ "

"Slow down, my friend," King Asgore interrupted, placing a large hand on Gaster's rapidly gesturing ones to still them. "You are a little too excited. We can't understand what you're saying."

Ducking his head briefly in embarrassment and taking a breath to calm himself a little, Gaster tried to speak more carefully and control his accent.

" _Thank you, Your Majesties. I would be honored to serve as your Royal Scientist._ "

* * *

Construction on the first settlement outside of Home, the one spear-headed by the furry monsters, was reaching the stage where monsters could almost live there. All the bridges along the way were complete and they would soon be working on pathways through water-filled caverns covered in sparkling stones. But more importantly, they had reached the point where they needed to do some further exploring.

Gaster knew how to reach the magma-filled chamber under the mountain. Or at least one such path. But it was a dead end. Only fire elementals and flying monsters would be able to cross and determine how to construct a bridge to whatever lay beyond. But after studying his map and extrapolating on some of the paths they hadn't explored as teenagers, Gaster suspected there might be other tunnels to the cavern. Perhaps there would be ways past the magma. And since he did the original exploration, he wanted to be the one to investigate the other paths.

But just like before, he didn't plan to go alone.

"J-just as c-cold as I remember," complained Erik.

Gaster just smiled at his old friend. The crab-like monster had grown larger in the years since their original adventure, but his dislike of the cold remained. His claws were a lot bigger as an adult than as a teenager and his exoskeleton had developed into a deep reddish shade. And while he now spent most of his time working in his store, Erik agreed to join the small exploration team alongside his wife.

Tixie hadn't grown much in comparison. She'd already been close to her adult size even back then. Her figure filled out her dress more since the birth of her children though. And her face had grown more mature and motherly. But there was still enough of her adventurous spirit for the rabbit monster to jump at the chance to grab a babysitter and drag Erik back out of Home.

Both had grown and changed so much over the years. Just as his parents were growing slower and stiffer in their movements compared to his childhood. And his friends and family would continue to age while Gaster remained the same. It was a fact he'd known all his life that was gradually becoming more evident. Unless something happened, he would outlive his friends and family. But as always, he pushed it from his mind. He couldn't change it and dwelling on that part of his future would do no good.

It was not just his friends accompanying him this time. A humanoid monster with a flat circle for a head, a smooth and coppery surface with no obvious facial features, was one of his new companions. Linc only came up to Gaster's shoulder, but he was a thoughtful monster with a talent for art. He would be doing the actual mapping this time. And to provide some strength and stability in case they encountered a dangerous area in their explorations, a large brown wolf monster from the Royal Guard would be joining them. She didn't really speak so much as she howled and she was a head taller than Gaster, but Great Wolf seemed loyal and dependable. Both of them should be wonderful additions as they map more of the Underground.

"So we're heading this way, right?" Trixie asked, gesturing to the left. "It's been a few years, but I don't remember us looking this way before."

Crunching through the snow, Gaster said, " _Based on what we mapped last time, this way leads to a river. We didn't plot most of the course, but the fact that it is flowing indicates that it leads somewhere. There has to be a way through. Perhaps even a way through or around the magma chamber._ "

It didn't take long for them to reach the river. While other places that they'd run into the stream was low enough for them to touch the water, this path led them to a cliff overlooking the river. From the vantage point, a large stretch of the river's journey could be observed. Linc started sketching immediately.

" _It appears that the river will bypass most of the darker caverns with the sparkling stones, though I suppose the various waterfalls, streams, and marshes might drain into the river,_ " said Gaster, leaning out as far as he could to see more. " _The river might curve closer to those caverns later on. Remember that one stream we encountered with a stronger current? It could be part of the same waterway._ "

"If the w-water is w-warmer than here, I'll help explore it later," Erik said.

Cuddling her husband close, Trixie said, "Look at that. We'll make an adventurer out of you yet."

Several things happened at the same time. Erik blushed an even brighter shade of red. Linc chuckled quietly as he continued to sketch. Great Wolf perked up her ears.

And the edge of the cliff crumbled beneath his feet, taking Gaster down with it.

He barely had a chance to realize he was falling, the strange sensation impossible to ignore, and he barely had a chance to hear the others calling his name. Then he hit the water hard, driving the breath from his body. And due to an unfortunate combination of Home lacking many deep bodies of water and skeletons not having the best buoyancy, Gaster never learned to swim and the current quickly pulled him down…

Down…

…down.

He'd read the human "Anatomy" book enough times to remember the description of their respiratory system. And while many monsters had lungs, hearts, and so on, their biology and anatomy varied far more than humans. For example, skeletons did not have internal organs. That did not mean they did not need things.

That didn't mean, Gaster's thoughts as chaotic and turbulent as the water choking him, he didn't need to _breathe_.

Gaster struggled wildly against the current, hands clawing at the water in a desperate attempt to force his head above the surface. Panic gripped him. He couldn't breathe. Water filled his mouth, choking and suffocating. His Soul lurched and raced frantically. He needed air.

His mind became fuzzy. His thoughts grew dull and sluggish. His Soul ached and burned as his body weakened. His limbs slowed their movements and became heavy. He… couldn't…

Suddenly, something snagged the collar of his sweater and hauled him upwards. And right before his vision went completely black, Gaster broke the surface and was dumped on a smooth surface that bobbed slightly under him.

While he didn't need to cough his non-existent lungs out to rid himself of the choking water, Gaster gasped desperately for air while excess liquid poured out, streamed off, and pooled around him. He couldn't stop shaking. Not from the undoubtedly cold water, skeletons being rather resistant to most temperatures. His body shook from how he nearly died. Gaster just stayed sprawled there, shaking and exhausted. His Soul slowly began to settle down again as he managed to breathe.

"Tra la la. That fall did not seem wise. A boat ride seems far more pleasant than tumbling beneath the river," said a strange and melodic voice.

His breathing still ragged and uneven, Gaster raised his head wearily. He appeared to be sprawled on the deck of a boat, the current pushing it along at a steady speed. And standing there, dripping from the rescue, was a strange monster. He couldn't make out any details other than a humanoid figure wrapped in a hooded robe.

"Are you quite all right? You are not a fish, but you tried breathing like one," continued the melodic voice.

Gaster gestured weakly to assure them. His breathing was starting to come back under his control, but his trembling hadn't ceased. He couldn't quite calm down. He didn't trust his voice at the moment. Gaster suspected that if he tried to speak, his words would be incomprehensible.

"Can you not talk? Or perhaps you speak with your hands instead?" The figure shrugged and said, "Regardless, your time on the water is coming to an end. We have arrived."

Before Gaster could ask what they meant, the boat came to a stop by the shore. He should get off the boat. Gaster knew he should climb up, get to shore, and look for the others. But his body felt like it weighed a ton and he couldn't seem to find the strength to try. His eye-lights were dim to the point of nearly being extinguished. Nearly drowning was clearly draining.

He needed to avoid falling like that in the future. It wasn't fun.

"Dr. Gaster?" called a more familiar voice, surprised and worried.

Even turning his head towards the shore felt exhausting. But it didn't take long to spot the source of the deep voice. Moving swiftly without any issues from his heavy armor and trailing cloak, the King of the Monsters reached the boat in no time. Gaster vaguely remembered that King Asgore was supposed to be visiting the developing settlement and encouraging the monsters there. And he might even intend to name the forming community. But Gaster really couldn't summon up the energy to think about it anymore. His mind felt muffled and stuffed.

"Dr. Gaster, are you all right? What happened to you?" asked King Asgore.

The amount of pity and concern in his expression was impossible to miss. Gaster couldn't even imagine what he looked like at that moment. His sweater soaked with water that was quickly starting to freeze, a limp and drenched lab coat clinging to his form, and barely able to push his head off the deck, Gaster suspected he appeared half-dead. And his trembling, though slowly easing, couldn't be reassuring to King Asgore.

"A high fall into the river left him shaken, but his fish impersonation included being fished out as well," said the hooded stranger.

" _I'm… I'm fine_ ," Gaster tried to assure the pair, but quickly realized his accent was too strong for them to understand.

Reaching over the skeleton's shoulder, King Asgore met his eye-lights worriedly. When they first met, Gaster would have been shocked and uncomfortable with the idea of royalty hovering over him like this and treating him so casually. But by now, Gaster knew that King Asgore didn't care of pomp, circumstance, and social standing overly much and would ignore it most of the time. So Gaster was not embarrassed that the King of the Monsters was fussing over him. It was simply that he didn't want to be in this situation and worrying someone.

As King Asgore finished his brief and concerned onceover of the skeleton, he quickly came to a conclusion and pulled off his cloak. He didn't give Gaster a chance to argue before wrapping the fabric around the soaked skeleton. Then he carefully helped Gaster to his feet, supporting his weight until he grew steady.

"Thank you for saving my Royal Scientist," said King Asgore gently. "I am afraid you don't look familiar to me. Have we met before?"

"Our paths have not crossed, though I would be a fool not to recognize the king under the mountain. Tra la la," the stranger said. "I am the Riverman. Or am I the Riverwoman? Well, it doesn't really matter."

"Gaster, you're alive!" shouted Trixie, running into view with the rest of the group and a few monsters from construction in tow.

For the next several moments, Gaster felt trapped as the small crowd questioned and reassured the skeleton in equal measure. Wrapped in the robe like it was a blanket, Gaster didn't want to be the center of all those worried and concerned monsters. He could breathe easily and the trembling had eased to the occasional shudder rather than constant. But he felt exhausted and his joints ached, ice forming there from his dunk in the river. He didn't want to deal with all these people. He just wanted to crawl off and sleep in his own bed for a while.

Gaster managed a small wave, trying to calm everyone down. Trixie and Erik were crowding him a little. And Great Wolf was sniffing him over. Needless to say, his attempts to reassure them weren't working.

"What lovely armor the king wears," the Riverperson said. "It reminds me of the Delta Rune. Do you know the meaning behind the symbol?"

"The Delta Rune?" asked King Asgore, blinking in surprise at the abrupt change in topic. "Well, no. We forgot its origin long ago. Long before even my father was born."

"Then none of you've heard of the prophecy? Tra la la. What a wonderful chance to see if you can listen and remember. Because many things and people are forgotten when they should be recalled," the Riverperson said in their musical voice. "You know of how the rune depicts the monsters with an angel above? The prophecy states an angel who has seen the Surface will descend from above and bring us freedom. And then the Underground will go empty."

That sparked off a lot of whispers that were no longer about Gaster's fall off a cliff. Any hint about the idea of monsterkind returning to the Surface was bound to hold their interest. All of them needed hope. And even a slim hope was worth clinging to. Hope, no matter the shape or form, was something that helped keep all monsters going.

But Gaster mostly appreciated no longer being the focus.

"So many wonderful things to discover if you spend enough time drifting along the current. And I've been here long enough to see those wonders," the Riverperson continued. "Like how the river flows all the way to the caverns filled with magma. Tra la la."

Gaster stared at the robed figure. All his plans to search and explore the Underground for an alternate path to the magma chamber and the Riverperson simply delivered the information casually. He didn't know if he wanted to laugh or cry. He nearly drowned at the very beginning of the search for answers that a monster sailing the river possessed.

…When did someone build a boat, let alone start traveling the river? How long had the Riverperson been there?

He couldn't wonder about it for long though. Gaster's eye-sockets felt as heavy as his limbs and he was struggling to keep them open. A good night's sleep should help banish the lingering effects of his fall into the river. And he really wanted to rest.

Apparently noticing his lagging strength, Trixie hurried over and took his hand.

"I think you might need to postpone our exploration for another day," she said. "Let's get you home, dried off properly, and let you warm up."

That plan sounded wonderful at the moment. Gaster gave a short nod. Then, remembering the borrowed cloak, he started to pull it off to return it.

"No, my friend," said King Asgore, stopping him. "Hold on to it for now. You may return it tomorrow."

He gave another short nod and let himself be led away. He didn't even try to ask what King Asgore decided to name the forming settlement.

 **Yes, skeletons in "Undertale" apparently need to breathe even though they clearly don't have lungs. Sans is clearly trying to catch his breath during the fight in the genocide run. Meanwhile, I had a surprisingly hard time trying to find a definitive answer for whether or not a skeleton would sink or float. Old bones versus fresh bones, salt water versus fresh water, a single bone versus an actual skeleton… Yeah, there's a lot of variables and very few clear answers. But it sounds like a human-shaped skeleton in fresh water would not have the greatest buoyancy ever.**

 **Anyway, I hope you're enjoying the story. And remember, feedback is always appreciated.**


	3. Congratulating

**Sorry that there are such long waits between chapters. I'm juggling a lot of things at the same time. And even if this story doesn't get a lot of people commenting on it, I do appreciate those who do read it. So thanks and enjoy the show.**

Though learning of another method of reaching the magma chamber turned out to be as beneficial to monsterkind as Gaster hoped, the largest benefit to his near-drowning experience was that it gave the other monsters time to devise choices for the name of the developing town rather than allowing King Asgore complete free rein. They gave him a list of names they liked for him to pick from. He still chose the least impressive option out of those offered, but "Snowdin" wasn't too bad. Especially compared to what happened years later. Waterfall and then Hotland were the obvious results of King Asgore's infamous naming abilities.

The towns and settlements sprung up as the monsters sought out new opportunities. They were lovely places, quite different than Home. Snowdin was cold and charming. Those with fur and a resistance to the temperatures found it to be a nice area to raise their families. There was space for children to play and the light reflected off the white snow made everything seem a little brighter.

Waterfall was more maze-like, weaving around and connected by bridges to span the various streams of water. Bright stones were embedded in the stone above, a sight that so many compared to the stars that supposedly glittered in the sky at night. It didn't take monsters long to adopt the tradition of wishing on "stars" using those stones. Then, someone deciding that they needed a more permanent method of recording their history that would outlast their books, a series of inscriptions were carved into the tunnels. More aquatic monsters also explored the caves and tunnels below the surface of the water, offering even more space for everyone.

And with these new places to live, monsters found the best ways to use their new environments. Cold-resistant crops were developed and planted in the area surrounding Snowdin while the forests were harvested for materials. Other plants were encouraged to flourish in the darker and wetter caverns of Waterfall alongside the already present flora. The newly-named echo flowers gave them a good starting point on how to encourage the crops to handle the environment. The king was surprisingly helpful when it came to horticulture. But Hotland didn't have the soil or moisture for such growth.

Thankfully, Gaster had different plans.

Bringing fire elementals on boats to Hotland was stressful, but certainly less so than traveling the entire length of Waterfall with so much water dripping and pouring. And once there, they were able to explore and even begin construction on walkways and platforms over the magma. In a relatively short span of time, other monsters could join them and work on the development of buildings and puzzles for Hotland. And of course, the Core.

Gaster had big plans for the Core. Dreams of powering every home in the entire Underground. But he also knew that he needed to be at least a little practical. They needed to start small and build their way up. He ensured his initial version would be easy to upgrade and expand. And while he and the other monsters constructed the device, Gaster also worked on running the thick and admittedly-inefficient cables to Home. If anyone should be the first to receive power from the Core, it should be the original city.

Even with everyone working to build the growing towns and spread out through the rest of the Underground, it took time. Building the Core took time. And then locating another large chamber past Hotland and further up, one that would be ideal for another settlement or even a city, took time. All of these things intended to help monsterkind took time. More time than what Gaster expected.

By the time he worked out all the kinks in the Core and power was brought to Home (through cables that he _knew_ would need to be replaced with something better someday), decades had passed. By the time a settlement began forming at the end of the cave system, so close to where monsters first entered the Underground so long ago, it had been nearly a century since he was officially made the Royal Scientist. He watched it all unfold. And he watched those around him fall.

His parents were gone. His father went first, but his mother didn't outlive him for long. Erik and Trixie were gone, mourned by their children and grandchildren. And it wouldn't be long before those grandchildren grew too old and frail in turn. He could already see the signs.

So many monsters that he'd known his whole life had grown old and turned to dust. It hurt to lose them. He knew it was coming. He'd known his entire existence that he would outlive them. Losing his family… His friends… Colleagues that he worked alongside… He'd known, but it still hurt.

With the exception of other Boss Monsters like the king and queen, he would lose everyone close to him. After a while, Gaster found it easier to bury himself in his work. He would rather focus on that instead.

After a while, however, he did start considering an idea. With how much time he spent in Hotland working on the Core, Gaster started considering that it would be easier to stay there. And since he was also the Royal Scientist, it made sense to build a proper lab. In his free time, he started sketching out designs. An upper floor for basic projects and a loft over it to serve as living quarters, but there would be a lower floor for more elaborate, large-scale, or dangerous experiments. There would be more than enough room for other scientists to join him to work, but the loft space would still give him some privacy.

And while certain that they would have no issue, Gaster felt that proposing the construction of a laboratory near so much magma might be something to discuss with the king and queen. Even with caution and safety measures, accidents could happen. And he could admit that when excited or distracted, he didn't always think things through.

He walked through the streets of Home, marveling at how empty it seemed. The days of his childhood where every inch of the city was pack full seemed so long ago. All the monsters were spreading out, almost fleeing from Home and the memories of the crowded existence. At this rate, it would soon be empty of everyone except the royal couple and a few of the more solitary monsters. And rumors suggested the king and queen may soon leave as well.

Their regular meetings for tea had trickled down to once every few months due to his new demands all across the Underground. But they still tried to meet up at their home. So Gaster walked in like always, carrying a stack of papers in his arms.

The scent of warm tea greeted the skeleton even before he spotted the royal couple. And while they always seemed pleased to see him, Gaster noticed that they appeared especially happy today. Queen Toriel couldn't stop smiling, her eyes bright and shining. And King Asgore looked so proud.

" _I came to discuss my plans for constructing a new laboratory and home in Hotland, but I suspect that you have news as well, Your Majesties_ ," he said without preamble. " _Am I to assume that the gossip is correct and you intend to move to the growing settlement at the far end of the Underground?_ "

Still beaming brightly, Queen Toriel said, "While that is not what we planned to tell you, it is true. The monsters are leaving Home and it makes more sense to live among our people. It will take time to build a new home there, but we do intend to go there."

"New Home," muttered King Asgore. "I like the sounds of that."

Narrowing her eyes at her husband, she said, "We need to have a serious discussion concerning names."

" _If your intended move is not what has the two of you so excited, then what is it? What is your news, Your Majesties?_ "

The pair exchanged glances. Just like so many times before, Gaster was impressed by their ability to communicate without words. The king and queen would always be his mental image of the ideal couple.

"We will be telling the rest of monsterkind soon, but Asgore and I thought it would be nice to share this news with those close to us," Queen Toriel said.

"And that includes you, my friend," said King Asgore.

Once more, the royal couple looked at each other. Somehow, they managed to grin even brighter than before. They couldn't hide how happy they were.

"You know that we have been married for a very long time," Queen Toriel said slowly.

Nodding, Gaster said, " _For longer than I have been alive_."

"Well, after so long together, it would seem that the time has come for our small family to grow larger," she said, beaming proudly.

Like when they offered him the job title of Royal Scientist, it took him a moment for the words to properly register. His mind seemed to stagger over the concept. Then it began to truly sink in.

" _Your_ _Majesties… Are you telling me that… Your Majesties, do you mean that you are having a child?_ "

Queen Toriel nodded enthusiastically while King Asgore clapped his shoulder in celebration. Gaster couldn't help smiling in response. Their reactions now made perfect sense. He had seen how much they cared about children over the decades and now they would have the chance to be parents. The mood was absolutely infectious.

Yes, this meant they would start aging. Both of them would invest a portion of their magic in their offspring throughout childhood. That's what happened with Boss Monsters. But almost everyone agreed that raising a family was worth living a normal lifespan instead.

And Gaster knew that after centuries of ruling together, King Asgore and Queen Toriel deserved to have something that clearly made them happy. A future heir to the throne would bring both them and the Underground so much hope and joy.

" _Congratulations, Your Majesties. I certainly didn't expect this news_ ," Gaster said, going slow to ensure that his enthusiasm didn't overcome his words.

The royal couple smiled at his words before leaning closer together, nuzzling their noses in a clear sign of affection. He was happy for them. This was wonderful. A child would bring so much light and love to these deserving monsters. The king and queen would get to raise a family, something that they had not done in the centuries that they spent together. Gaster was truly happy for them.

And if that meant that even they would someday be gone and he would be alone, then so be it.

" _How will you tell the rest of the Underground this news?_ "

"There will be an announcement at the end of the week," said King Asgore. "And thank you, my friend. This will change everything for us."

* * *

She remembered the distant days on the Surface before the War, so Toriel knew that anything to do with pregnancy was no easy for anyone. Human or monster. Creating a new little Soul and then a body took quite the investment of strength and magic. Thankfully for a couple of Boss Monsters, both of them were contributing magic rather than just the one carrying the child. And then childbirth caused quite a bit of strain and took a lot of energy. She knew to expect the pain and exhaustion, but she was strong, healthy, and cared for by skilled healers.

Before she knew it, the entire thing was over and a tiny whimpering bundled was settled into her waiting arms.

She was a mother. It didn't feel real even a few days later, the precious young monster truly being hers. She and Asgore kept being distracted by the infant. His little fingers and toes, his soft white fur, and his tiny floppy ears were all so perfect. Their son was perfect and she couldn't love him more if she tried.

Asgore's enthusiasm at being a father also ran high. But she managed to have at least some influence on the name anyway. Otherwise the young Boss Monster might have ended up as "Torgore" or something that sounded like "royalty." At least they chose one that seemed pleasant and rolled easily off the tongue.

Cradling her child close, Toriel hummed a soft lullaby to him. Asriel yawned in response. She was happy that he seemed settled. They might have spent the last few days with just family, but today there would be company. She would prefer Asriel to be in a good mood when he met his visitor.

Opening the door, Asgore entered the room and said, "This way, my friend."

Her husband led Dr. Gaster towards Toriel. The skeleton looked a little uncomfortable and awkward as he approached, as if he wasn't certain what was expected of him. Poor guy. He always knew what to say or do when it came to science. But children were very different.

" _Hello, Your Majesty_ ," he said. " _News of the young prince's birth has already spread. You must be proud._ "

"And very happy," said Toriel. "Would you like to hold Asriel?"

He stiffened at her words, his eye-lights shrinking briefly. Then he managed to shrug off the worst of that panic and gave her a nod. Toriel carefully helped rearrange his arms so that he was holding the infant, supporting Asriel's head and cradling him against his grey sweater and lab coat. Asriel didn't even make a _meep_ of complaint over the transfer. And after a few moments of staring at the small creature in his arms as if afraid he would drop him, Gaster gradually eased into a more relaxed position.

"I think he looks a bit like me," said Asgore.

"Perhaps if Asriel had a beard," she said with a chuckle. Turning back towards the skeleton, she said, "You seem to be a natural at this. Have you held a child before, Dr. Gaster?"

" _In the past_ ," admitted Gaster, a distant expression briefly crossing his face. " _There were a few. My friends, Erik and Trixie, had several children. And then they had children. I was not as close with those that came afterwards, so it has been a while._ "

Toriel felt her smile waver briefly. Both she and Asgore had dealt with the struggles of outliving those around them, though that issue would no longer apply. They'd come to terms with it several centuries ago. But when it was happening to them, they'd always had each other.

Gaster, on the other hand, might not be handling it well. Looking back, she couldn't remember him mentioning any friends in several decades. Even if she didn't spend as much time with him as her husband, surely she would have heard something? Asgore hadn't mentioned the skeleton talking about friends as far as she could recall. She started wondering and worrying that Gaster might be isolating himself to an extent to avoid the pain of further loss. And that wouldn't do him any good.

He needed to deal with monsters outside of work. Gaster needed more than the occasional tea with the royal family. He needed friends. And maybe more. Toriel would have to work on that. Between Asgore and herself, they might be able to help him even while juggling their normal royal duties and their son.

"Have you ever considered a family of your own, my friend?" asked Asgore gently.

Still staring down at the child in his arms, Gaster said, " _That is not likely to happen, Your Majesty. There is no one out there for me._ "

"Have you even looked? There are a few very nice Boss Monsters out there. And several skeletons if you prefer," Toriel said. "There is an entire Underground of possibilities."

"And there are so many monsters who would love to meet the Royal Scientist,' said Asgore.

"Especially one so handsome."

Toriel chuckled lightly as he stammered and ducked his skull down in response to the compliment. He was surprisingly easy to fluster like that. She looked forward to the day that he found someone who made him react like that all the time.

"But I am serious, Dr. Gaster," she continued. "If you were ever to find someone, would you be interested in having a family someday? A spouse? Perhaps children?"

Staring down at the now-yawning infant in his arms, Gaster said quietly, " _As I have already stated, it is unlikely that will ever happen. Even if there was a monster out there for me, I am too busy with my projects for such things, Your Majesties. It is better this way._ " He rocked Asriel gently, something a little wistful in his expression. Then, even quieter than before, he added, " _Though it would be nice_."

* * *

Asriel scurried down the halls of Home, solving the puzzles with practiced ease. This part of the Underground was empty just as it normally was. There weren't many monsters left in Home. Mom, Dad, Uncle Gaster, and all the other grownups told him that it used to be really crowded, but he couldn't imagine that. Almost everyone had moved to Snowdin, Waterfall, Hotland, and even New Home. And since their house and even the fancy castle for meeting people were almost finished, Asriel and his family would be moving soon as well. But before that happened, there was still time for a last tiny adventure.

He wasn't supposed to go so far alone. His mom and dad told him not to do it. And he usually did what he was supposed to. But everyone who ever lived in Home would go to the end of the cave tunnels at least once. They would go and glimpse that tiny sliver of sunshine that trickled down from the Surface. And if Asriel was going to move to the other side of the Underground, he intended to see it before he left.

The young goat-like monster jumped into a crinkly pile of leaves, laughing cheerfully. Even as a mature and accomplished five-year-old, no one could resist playing in colorful leaves. And why go on an adventure if you couldn't have fun?

He wasn't sure how long he wandered further and further. Asriel only knew that the purple walls eventually gave way to more natural stone at the bottom of a staircase. And that meant he must be getting close. Mom and Dad were going to be so mad when he made it back. But it would be worth it. He would get the tiny glimpse of sunlight. That would be even better than the glittering stones in Waterfall, the ones that the older monsters said looked like the stars from stories.

As he entered a dark cavern, Asriel heard something. The sound echoed off the walls, drawing him closer. At first, Asriel couldn't figure out what he was hearing and followed out of curiosity. Only when he reached the entrance to the final chamber did Asriel recognize the sound.

Someone was crying.

"It sounds like it came from over here..." he muttered as he rounded the corner.

A light shone down, illuminating a small shape on a patch of green plants. Their face was down, hidden by brown hair dangling around their features. He could see two arms and two legs. They wore a striped sweater, so they must be a child. The sweater was worn, torn in places, and dirty to the point where he couldn't be certain of the original colors, but certainly striped. And they seemed to be the same size as Asriel.

When he took another step forward, the young monster accidentally kicked a small rock and sent it skittering across the ground. And that was apparently enough to alert the new arrival to his presence.

Their head popped up, eyes wide and searching. Asriel could see more of their pale skin now, though their cheeks were a bit rosier. Tears streaked down their face and their expression was a mixture of pain and fear.

And they weren't any kind of monster that Asriel knew of. In fact, if he didn't know any better, he would almost think that the scared and hurt child was a human.

But more important, they were scared and hurt.

Crouching down and extending a hand, Asriel said, "Oh! You've fallen down, haven't you? Are you okay? Here, get up."

Eyes haunted and distrustful, they nodded slowly. Then, keeping their movements slow and cautious, they accepted Asriel's offered hand. His smile was returned by a more timid one.

"I am Chara," said the child quietly.

"Chara, huh? That's a nice name. My name is Asriel."

"Are… are you going to eat me?"

Asriel couldn't help laughing at the question. It was just too silly. Chara scowled grumpily.

"You are a monster, are you not? The stories say that monsters eat people," said Chara.

"And _our_ stories say that humans kill everyone. Do you want to kill me?"

Chara shook their head sharply, a flash of some darker emotion briefly crossing their face before vanishing. On the bright side, some of their fear seemed to be fading. Asriel carefully helped them to their feet.

"If you promise not to kill anyone, I promise no one will eat you," Asriel said. "Come on. You're hurt and Mom can help. She can make anything better."

* * *

Asgore looked over the list that his wife compiled. She'd been adding and subtracting to it over time, updating it as she tried different things. She was very enthusiastic about this. Toriel had been working on it for almost eight years. And she was not one to surrender easily.

Levy, a brilliant avian monster with a talent for architecture. Barb, an outgoing chemist with thorny hair and smooth bark. Hawkins, another avian monster who loved working with numbers. Krackle, a friendly fire elemental who already seemed to have warm feelings towards Gaster.

And if he preferred another skeleton, Toriel picked out a few promising options. Georgia. Consolas. Sistina. Verdana. All lovely skeletons with at least some interest in science.

The list was very thorough, describing the features that she felt would be the most attractive to Gaster. Asgore had to give his wife credit. Toriel could be quite the enthusiastic matchmaker.

"Hey, Dad!" called Asriel, feet pounding on the floor as he and his sibling raced into the house. "Uncle Gaster is early. We saw him coming towards the house."

Smiling briefly as he put away the list in his desk, Asgore said, "Is that a fact? Then I better finish getting ready. Could you help and fill the tea kettle with water for me?"

Both of his children nodded at his request, though Asriel was naturally more enthusiastic about it. Chara was always more subdue than their brother. They were quiet and shy around most monsters other than Asriel. But while they still had their occasional dark days from whatever happened in their past, Chara seemed relatively happy in the family.

The last three years had been good ones.

Asgore pulled on the comfortable hand-knit sweater, the one with the words "Mr. Dad Guy" on it. He tried to wear it whenever he was home with his children. Chara seemed to notice when he wore their gift and he wanted their adopted child to know how much they loved Chara. If wearing the sweater reassured them that he wanted their smart and quiet human child in the family, he would happily wear it until the sweater unraveled from age.

He loved both of his children. He and Toriel adored Asriel from the moment he was born. Then he came home one day with a limping, skittish, and young human. And while it took time to gain the child's trust, Chara was considered a Dreemurr almost instantly. They brought Chara with them when they moved to New Home and now it was like there had always been two children.

As Asgore stepped out of his room, he heard enthusiastic talking. He couldn't help smiling at the sound. It would seem that Gaster was already in the house. And it also sounded like Asriel was already telling the Royal Scientist all about their last few days.

Over the years, Gaster spent enough time around the household for tea and the occasional casual update on progress that Asriel practically grew up with the skeleton. Thankfully he didn't seem to mind being referred to as "Uncle Gaster" since Asriel started calling him that almost as soon as he could speak. Chara was less comfortable with using that address for him. But either way, Gaster seemed fond of the children. While he didn't seem eager to connect with other monsters outside of a professional setting, even with Toriel's matchmaking attempts, Gaster always had time for the two of them.

"And we went all the way to Waterfall yesterday," continued Asriel excitedly. "Even past the dump. The stones in the ceiling were so amazing. We both made wishes on them. Then there were the really big waterfalls. They were _huge_. And we read the inscriptions on the walls, the ones talking about how we ended up in the Underground after the War."

" _It sounds like you had a busy day_ ," Gaster said, grinning down at the bouncing child. " _I am guessing that both of you had a good time, Your Highness?_ "

"Yep. It was fun."

"Are they true?" asked Chara abruptly.

" _Excuse me?_ "

"The inscriptions on the walls. Is everything written on them real? Did everything occur as described?"

Tilting his head, Gaster said, " _As far as I am aware, it should be accurate._ " His tone taking on a hint of amusement, he added, " _Though I was not around for those events personally. I am not quite_ _ **that**_ _old._ "

"I see…"

As Chara trailed off thoughtfully, Asgore cleared his throat. Three sets of eyes turned towards the king abruptly, making it clear that they hadn't noticed his entrance. Asgore smiled at them.

"I'm sorry to interrupt, but I suppose I should get that tea started," he said. "Chara? Asriel? If you want to play outside while we visit, please stay in the yard. Tori will be home from the meeting with the Temmies soon and you don't want to miss dinner."

"Sure, Dad," said Asriel. "Come on, Chara."

He watched as the two children in twin striped-sweaters hurried out the door. Asgore couldn't help smiling at the pair. They were so precious.

He had a wonderful wife, two beautiful children, and a cozy home to share with them. They were his entire world. Nothing could ruin this absolute happiness.

* * *

"Psst… Chara… Please… wake up… I don't like this plan anymore. I… I… No, I said… I said I'd never doubt you. Six, right? We just have to get six… And we'll do it together, right?"

 **And if you've played the game, you know what comes to next. Things in the Underground are about to get a bit more depressing. But we all knew it was coming. There was no avoiding what happens to the kids.**


End file.
